As California moves closer to the rollout of a major voting overhaul law, new research from UC Davis suggests that some racial and ethnic groups could be left behind under the new system.

The research, released Thursday by the university's California Civic Engagement Project, shows large disparities among racial and ethnic groups regarding mail voting and the degree to which they trust the U.S. Postal Service, which is a key component to voting by mail.

The new law, which was signed by Gov. Jerry Brown last fall, is expected to shutter many neighborhood polling places. Instead, counties will have the option to switch to "vote centers," where voters can cast ballots over a period of up to 10 days. The new system will also rely heavily on an increased use of voting by mail. In most parts of the state, all registered voters will automatically receive a vote-by-mail ballot.

The change is set to begin in a handful of counties starting next year and is expected to help reduce the cost of elections. L.A. County is expected to adopt the new voting system in 2020. Orange County's Board of Supervisors recently halted the 2018 rollout, even though the registrar had been a proponent of the plan.

As many counties move to implement the new voting system, some worry that groups who don’t vote by mail in large numbers may be left out.

The survey found that among respondents who don’t send in their ballots via the mail, nearly half of Asians said they didn’t trust the postal service to deliver their ballots safely and on time.

African-Americans and Latinos also mistrusted the post office in larger numbers — at rates of 32 and 29 percent, respectively. Only 21 percent of white respondents felt the same way.

In addition, voter records show Latinos vote by mail less frequently in California than the total population of registered voters.